JP2009106018A - Charging device and charging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device which can reduce voltage variation at the completion of charging of power storing elements constituting a battery pack, even at rapid charging, without enlarging the circuits or increasing the cost. <P>SOLUTION: The charging device 1 comprises an ECU 40, wherein a voltage detection part 42 for detecting the voltage values of the power storing elements B1 to Bn; a charging characteristics acquisition part 44 for acquiring the charging characteristics of the power storing elements B1 to Bn, based on the voltage value change during charging of the power storing elements B1 to Bn; and a charging start state setting part 46 for setting a target charging start voltage for each power storing element B1 to Bn, based on a preset target charging completion voltage and the charging characteristics of the power storing elements B1 to Bn, are constructed functionally; a DC-DC converter 20 for supplementally charging the power storing elements B1 to Bn so that the voltage values of the power storing elements B1 to Bn agree with the target charging start voltage; and a charger 30 for rapidly charging the battery pack 10, after the supplemental charging of the power storing elements B1 to Bn. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charging device and a charging method, and more particularly, to an assembled battery charging device and a charging method in which a plurality of power storage elements are connected in series.

In recent years, in hybrid vehicles and electric vehicles, an assembled battery in which a plurality of secondary batteries (storage elements) such as lithium ion batteries are connected in series is used. Here, it is important to use the secondary battery so that the voltage value of the secondary battery is maintained within a predetermined range in order to extend the life of the secondary battery and improve the utilization efficiency of electric power. However, since the voltage value of each secondary battery varies due to variations in internal resistance, ambient temperature, etc., in an assembled battery configured by connecting a plurality of secondary batteries, the voltage value of the entire assembled battery is managed / controlled. In addition, the voltage value of each secondary battery is managed / controlled (hereinafter also referred to as “equalization”) so as to suppress variations in the voltage value of each secondary battery (see, for example, Patent Document 1 below).
JP 2003-289630 A

  When charging the battery pack while equalizing the secondary batteries, the charging current is limited by the current value that can be passed through the equalizing circuit, and thus the charging time may be long. Or, equalization may not end before the end of charging. This tendency is particularly remarkable when the voltage variation of the secondary battery is large or when quick charging is performed. Here, if the value of the current that can be passed through the equalization circuit is increased and applied to rapid charging, the equalization circuit is increased in size and cost. On the other hand, when charging the assembled battery after equalizing the voltage of the secondary battery, there is a risk that the voltage value of each secondary battery at the end of charging may not be uniform due to variations in charging characteristics due to variations in internal resistance, etc. .

  The present invention has been made in order to solve the above-mentioned problems, and without causing an increase in circuit size and cost, a voltage at the end of charging of each storage element constituting the assembled battery even during rapid charging. It is an object of the present invention to provide a charging device and a charging method capable of reducing variations.

  A charging device according to the present invention is an assembled battery charging device configured by connecting a plurality of power storage elements in series, and is detected by a voltage detection means that detects a voltage value of each of the power storage elements, and the voltage detection means. Based on the voltage value change during charging of each storage element, the charging characteristic acquisition means for acquiring the charging characteristic of each storage element, the preset target charge state at the end of charging, and the charging characteristic acquisition means Based on the charging characteristics, charging start state setting means for setting the target charging state at the start of charging for each power storage element, and based on the target charging state at the start of charging set by the charging start state setting means, Charge state adjustment means for adjusting the charge state of the storage element, and charging means for executing charging of the assembled battery after the charge state of each storage element is adjusted by the charge state adjustment means. .

  The charging method according to the present invention is a method for charging an assembled battery configured by connecting a plurality of power storage elements in series, and includes a voltage detection step for detecting a voltage value of each power storage element, and a voltage detection step. Based on the detected voltage value change during charging of each storage element, a charging characteristic acquisition step for acquiring the charging characteristic of each storage element, a preset target charging state at the end of charging, and a charging characteristic acquisition step Based on the charge characteristics acquired in step 1, the charge start state setting step for setting the target charge state at the start of charge for each power storage element, and the target charge state at the start of charge set in the charge start state setting step A charge state adjustment step for adjusting a charge state of each power storage element; and after a charge state of each power storage element is adjusted in the charge state adjustment step, Characterized in that it comprises a charging step of performing electrodeposition.

  According to the charging device or the charging method of the present invention, the charging characteristics of each storage element obtained from the target charging state at the end of charging (hereinafter also referred to as “target charging end state”) and the voltage value change during charging are obtained. Based on this, a target charge state at the start of charging (hereinafter also referred to as “target charge start state”) is set for each power storage element, and the charge state of each power storage element is adjusted based on the set target charge start state. After that, the battery pack is charged. That is, the charging state of each power storage element is adjusted in advance (before charging is started) in consideration of the target charging end state and the charging characteristics of each power storage element. For this reason, it is possible to align the state of charge of all the storage elements to the target charge end state at the end of charge. In addition, according to the charging device or the charging method of the present invention, the charging state of each power storage element is adjusted independently prior to charging the assembled battery. It can also handle charging.

  In the charging device according to the present invention, the charging start state setting means starts charging so that the charging state of all the power storage elements constituting the assembled battery coincides with the target charging state at the end of charging when the charging of the assembled battery ends. It is preferable to set a target charging state for the hour.

  Further, in the charging method according to the present invention, in the charging start state setting step, at the end of charging of the assembled battery, the charging state of all the power storage elements constituting the assembled battery matches the target charging state at the end of charging. It is preferable to set a target charging state at the start of charging.

  In this way, it is possible to reliably align the state of charge of all power storage elements to the target charge end state at the end of charge.

  In the charging device according to the present invention, the charging start state setting means sets the target voltage value at the start of charging for each power storage element based on the target voltage value at the end of charging and the charging characteristics, and the charging state adjustment means It is preferable to perform supplementary charging or discharging of each storage element so that the actual voltage value of each storage element matches the target voltage value at the start of charging.

  Further, in the charging method according to the present invention, in the charging start state setting step, the target voltage value at the start of charging is set for each power storage element based on the target voltage value at the end of charging and the charging characteristics, and the charging state adjustment is performed. In the step, it is preferable to perform supplementary charging or discharging of each power storage element so that the actual voltage value of each power storage element matches the target voltage value at the start of charging.

  In this case, considering the target voltage value at the end of charging (hereinafter also referred to as “target charging end voltage”) and the charging characteristics of each power storage element, the actual voltage value of each power storage element and the target voltage value at the start of charging (hereinafter referred to as “charge target voltage”) Each storage element is precharged or discharged in advance (before charging is started) so that the “target charging start voltage” also matches. Therefore, it is possible to make the voltage values of all the storage elements equal to the target charging end voltage at the end of charging.

  On the other hand, in the charging device according to the present invention, the charging start state setting means sets the target supplementary charging amount before starting charging for each power storage element based on the target voltage value at the end of charging and the charging characteristics, and adjusts the charging state. It is also preferable that the means perform a supplementary charge or discharge of each power storage element according to the target supplementary charge amount.

  Further, in the charging method according to the present invention, in the charging start state setting step, based on the target voltage value at the end of charging and the charging characteristics, a target supplementary charging amount before starting charging is set for each power storage element, and the charging state adjustment is performed. In the step, it is also preferable to perform a supplementary charge or discharge of each power storage element according to the target supplementary charge amount.

  In this case, in consideration of the target charging end voltage and the charging characteristics of each power storage element, supplementary charging or discharging is performed in advance (before starting charging) according to the target supplementary charging amount of each power storage element. Therefore, it is possible to make the voltage values of all the storage elements equal to the target charging end voltage at the end of charging.

  The power storage element is preferably a lithium ion battery. In this case, since overcharge of the lithium ion battery can be prevented and appropriate voltage management can be performed, variation in deterioration of the lithium ion battery can be suppressed.

  According to the present invention, the target charge state at the start of charging is set for each power storage element based on the target charge state at the end of charging and the charging characteristics of each power storage element, and the set target charge state at the start of charging is set. Therefore, the battery pack is charged after adjusting the state of charge of each power storage element, so that each of the batteries constituting the battery pack can be quickly charged without increasing the size and cost of the circuit. It is possible to reduce voltage variation at the end of charging of the storage element.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  First, the structure of the charging device 1 which concerns on embodiment is demonstrated using FIG. 1, FIG. 2 collectively. FIG. 1 is a diagram illustrating an overall configuration of the charging device 1. FIG. 2 is a diagram illustrating a configuration of a voltage detection circuit included in the electronic control device that constitutes the charging device 1.

  The battery charger 1 is an assembled battery in which a plurality of power storage elements B1, B2, B3, B4 to Bn-3, Bn-2, Bn-1, and Bn (where n is a natural number) are connected in series. More specifically, the voltage value of each of the power storage elements B1 to Bn constituting the assembled battery 10 is set to a target charge end voltage (for example, 4.2 V) set in advance at the end of charging. ) To charge the battery pack 10 so as to match.

  Therefore, the charging device 1 mainly includes a switch matrix 12 for selecting a voltage detection target and a power storage element to be supplemented from among the plurality of power storage elements B1 to Bn constituting the assembled battery 10, and the power storage elements B1 to B1 before charging. Control of the DC-DC converter 20 that supplementarily charges Bn, the charger 30 that rapidly charges the assembled battery 10 after the storage elements B1 to Bn are supplementally charged, and the switch matrix 12, the DC-DC converter 20, and the charger 30 Is provided with an electronic control device (hereinafter referred to as “ECU (Electric Control Unit)”) 40. Here, the DC-DC converter 20 functions as a charging state adjusting unit described in the claims, and the charger 30 functions as a charging unit described in the claims.

  As the electricity storage elements B1 to Bn, lithium ion batteries are preferably used. However, instead of lithium ion batteries, secondary batteries that can be charged / discharged, such as nickel cadmium batteries, large-capacity capacitors (ultracapacitors), modules that are configured by connecting multiple secondary batteries or large-capacity capacitors in parallel, etc. Can also be used.

  The switch matrix 12 has photorelays R1, R2, R3, R4 to Rn-2, Rn-1, Rn, and Rn + 1 that select a power storage element that is a voltage detection target and an auxiliary charge target from among the power storage elements B1 to Bn. is doing.

  One end of the photorelay R <b> 1 is connected to the negative electrode of the power storage element B <b> 1, and the other end is connected to the second bus 16. One end of the photorelay R <b> 2 is connected to the positive electrode of the electric storage element B <b> 1 (the negative electrode of the electric storage element B <b> 2), and the other end is connected to the first bus 14. In addition, one end of the photorelay R3 is connected to the positive electrode of the electric storage element B2 (the negative electrode of the electric storage element B3), and the other end is connected to the second bus 16. One end of the photorelay R4 is connected to the positive electrode of the electric storage element B3 (the negative electrode of the electric storage element B4), and the other end is connected to the first bus bar 14. Similarly, one end of the photorelay Rn is connected to the + pole of the storage element Bn-1 (the −pole of the storage element Bn), and the other end is connected to the first bus 14. One end of the photorelay Rn + 1 is connected to the positive electrode of the power storage element Bn, and the other end is connected to the second bus 16.

  When the storage element B1 is selected as a voltage detection target (or auxiliary charge target), the photorelay R1 and the photorelay R2 are turned on. Further, when the storage element B2 is selected, the photorelay R2 and the photorelay R3 are turned on. Similarly, when power storage element Bn is selected, photorelay Rn and photorelay Rn + 1 are turned on.

  The first bus 14 is connected to the voltage detector 42 of the ECU 40 via the photorelay R11, and the second bus 16 is connected to the voltage detector 42 of the ECU 40 via the photorelay R12. Details of the voltage detector 42 will be described later. The photorelays R11 and R12 have a function of executing / stopping voltage detection of the storage elements B1 to Bn. When reading the voltage values of the selected storage elements B1 to Bn, the photorelays R11 and R12 Is turned on and when the voltage value reading is stopped, the photorelay R11 and the photorelay R12 are turned off.

  That is, when the photorelay connected to both electrodes of the voltage detection target storage element and the photorelays R11 and R12 are turned on, the voltage of the selected storage element is placed on the first busbar 14 and the second busbar 16. The voltage is output and input to the voltage detection unit 42 via the first bus 14, the second bus 16, and the photorelays R11 and R12. By sequentially repeating this operation for all the power storage elements B1 to Bn, the voltage values of all the power storage elements B1 to Bn are read into the ECU 40. In addition, ON / OFF of photorelay R1-Rn + 1 and photorelay R11, R12 is controlled by ECU40.

  The switch matrix 12 has a function of selecting a storage element that is a target for supplementary charging in addition to a function of selecting a storage element that is a target for voltage detection. An insulating DC-DC converter 20 is connected to the first bus bar 14 and the second bus bar 16 via a polarity conversion matrix 22. A known DC-DC converter 20 can be used.

  The polarity conversion matrix 22 is composed of four photorelays R21, R22, R23, and R24, and has a function of switching the polarity of the voltage output to the first bus bar 14 and the second bus bar 16. One end of each of the photorelays R21 and R23 is connected to the second bus 16. The other end of the photorelay R21 is connected to the + terminal of the DC-DC converter 20, and the other end of the photorelay R23 is connected to the-terminal of the DC-DC converter 20. Are connected to each. On the other hand, one end of each of the photorelays R22 and R24 is connected to the first bus 14, the other end of the photorelay R22 is connected to the negative terminal of the DC-DC converter 20, and the other end of the photorelay R24 is connected to the DC-DC converter 20. Each is connected to the + terminal. In addition, ON / OFF of photorelay R21, R22, R23, R24 is also controlled by ECU40.

  Here, for example, when performing supplementary charging for the storage element B1, the photorelays R1 and R2 are turned on, the photorelays R23 and 24 are turned on, and the photorelays R21 and 22 are turned off. The positive pole of power storage element B1 and the positive terminal of DC-DC converter 20 are connected, and the negative pole of power storage element B1 and the negative terminal of DC-DC converter 20 are connected. Further, for example, in the case where auxiliary charging is performed on the storage element B2, the photorelays R2 and R3 are turned on, the photorelays R21 and 22 are turned on, and the photorelays R23 and 24 are turned off, thereby storing power. The positive pole of element B2 and the positive terminal of DC-DC converter 20 are connected, and the negative pole of power storage element B2 and the negative terminal of DC-DC converter 20 are connected. In this manner, supplementary charging is performed for each of the power storage elements B1 to Bn. It should be noted that all of photorelays R21, R22, R23, and R24 are turned off when auxiliary charging is not performed for power storage elements B1 to Bn.

  A charger 30 that rapidly charges the assembled battery 10 is connected in parallel to both ends of the assembled battery 10 (that is, the negative electrode of the electric storage element B1 and the positive electrode of the electric storage element Bn). A known quick charger can be used as the charger 30.

  The ECU 40 includes a CPU (Central Processing Unit) that performs calculations, a ROM (Read Only Memory) that stores programs for causing the CPU to execute each process, and a RAM (Random Access Memory) that stores various data such as calculation results. The photorelays R1 to Rn, R11, R12, and R21 to R24 are configured to have a driver circuit and the like.

  With such a configuration, the ECU 40 has the voltage detection unit 42 that detects the voltage value of each of the power storage elements B1 to Bn, and each power storage element B1 to Bn based on the voltage value change during charging of each power storage element B1 to Bn. Based on the charge characteristic acquisition unit 44 that acquires the charge characteristics of the battery, the preset target charge end voltage, and the charge characteristics of the power storage elements B1 to Bn, the target charge start voltage (for each of the power storage elements B1 to Bn ( Alternatively, the charging start state setting unit 46 for setting the target supplementary charging amount) is functionally constructed. Here, the voltage detection unit 42 functions as a voltage detection unit described in the claims, and the charging characteristic acquisition unit 44 functions as a charging characteristic acquisition unit. Moreover, the charge start state setting part 46 functions as a charge start state setting means described in the claims.

  The voltage detection unit 42 has a voltage detection circuit that detects the voltage values of the storage elements B1 to Bn, and is selected by sequentially switching the ON / OFF states of the photorelays R1 to Rn as described above. The voltage value of each electrical storage element B1-Bn is read. Here, the configuration of the voltage detection circuit included in the voltage detection unit 42 is shown in FIG. Both terminals of the primary coil of the pulse transformer with a midpoint tap (hereinafter simply referred to as “pulse transformer”) PT are connected to the first bus 14 and the second bus 16, respectively. On the other hand, both terminals of the secondary coil of the pulse transformer PT are connected to the input terminal of the A / D converter AD via the diode D1 and the diode D2, respectively. The midpoint tap of the pulse transformer PT is connected to the GND terminal of the A / D converter AD. The voltages of the storage elements B1 to Bn input via the pulse transformer PT are converted from analog values to digital values by the A / D converter AD and output to the charging characteristic acquisition unit 44.

  The charging characteristic acquisition unit 44 acquires the charging characteristics of each of the power storage elements B1 to Bn based on the relationship between the elapsed time from the start of charging and the voltage values of the power storage elements B1 to Bn. For example, when a voltage change as shown by a solid line in FIG. 3 is detected during charging by detecting a voltage value at predetermined time intervals, the power storage elements B1 to B1 are approximated by approximating the solid line with an approximate expression. Obtain the charge characteristics of Bn. In addition, as an approximation algorithm, well-known algorithms, such as a linear approximation, an exponential approximation, a logarithmic approximation, can be used, for example. Note that the charging characteristics of each of the power storage elements B <b> 1 to Bn acquired by the charging characteristics acquisition unit 44 are output to the charging start state setting unit 46.

  The charge start state setting unit 46 sets a target charge start voltage for each power storage element based on a preset target charge end voltage (for example, 4.2 V) and the charge characteristic acquired by the charge characteristic acquisition unit 44. To do. That is, the charging start state setting unit 46 is configured to store the storage elements B1 to B1 so that the actual voltage values of all the storage elements B1 to Bn constituting the assembled battery 10 coincide with the target charging end voltage when the charging of the assembled battery 10 is completed. A target charging start voltage is set for each Bn. More specifically, when charging is performed at a predetermined time rate (for example, 3C), the deviation between the charging end voltage predicted from the charging characteristics (approximate expression) and the target charging end voltage is added to the voltage value before charging. The value is set as the target charging start voltage.

  In the example shown in FIG. 3, the voltage value before charging is 3.5 (V), and the charging end voltage estimated when charging at a time rate of 3C is 4.0 (V). A value 3.7 (V) obtained by adding a deviation 0.2 (V) from the end voltage to a voltage value 3.5 (V) before charging is the target charging start voltage. Note that the deviation between the charge amount obtained by integrating the approximate expression and the charge amount required to charge up to the target charge end voltage, that is, the charge amount predicted to be insufficient at the end of charge (in FIG. 3 May be set as the target supplementary charge amount.

  ECU 40 drives photorelays R1 to Rn, R21 to R24, and DC-DC converter 20, and each power storage element B1 to B1 so that the actual voltage value of each power storage element B1 to Bn matches the target charging start voltage. Supplementary charging of Bn is performed. Here, in the charge start state setting unit 46, when the target supplementary charge amount is set instead of the target charge start voltage, supplementary charging is performed on the storage elements B1 to Bn according to the target supplemental charge amount. In addition, instead of supplementarily charging each power storage element B1 to Bn, by discharging each power storage element B1 to Bn, the actual voltage value of each power storage element B1 to Bn may be matched with the target charging start voltage. Good. After the completion of the auxiliary charging, the ECU 40 drives the charger 30 and charges the assembled battery 10 until the actual voltages of the power storage elements B1 to Bn match the target charging end voltage.

  Next, the operation of the charging device 1 and the charging method will be described with reference to FIG. FIG. 4 is a flowchart showing the processing procedure of the charging process by the charging apparatus 1. This process is mainly performed by the ECU 40, and is repeatedly executed at a predetermined timing from when the power supply of the charging apparatus 1 is turned on to when it is turned off.

  In step S100, the charger 30 is driven, and charging of the assembled battery 10 is started. Here, CC (constant current charging) is preferable as the charging method in order to stabilize the voltage detection values of the power storage elements B1 to Bn.

  In subsequent step S102, the photorelays R1 to Rn + 1 and the photorelays R11 and R12 are driven, and the voltage values of the power storage elements B1 to Bn are sequentially detected. The detection result is stored in a memory (RAM). Then, when charging is performed until the voltage value of any one of the power storage elements B1 to Bn matches a predetermined target charging end voltage, driving of the charger 30 is stopped and charging of the assembled battery 10 is ended. (Step S104).

  After the charging of the assembled battery 10 is completed, in step S106, the charging characteristics (approximate expression) of each of the power storage elements B1 to Bn are based on the relationship between the elapsed time from the start of charging and the voltage values of the power storage elements B1 to Bn. To be acquired. The acquired charging characteristics (approximate equations) of the respective storage elements B1 to Bn are stored in the memory (step S108).

  Subsequently, in step S110, discharge for an electric load such as an electric motor connected to the assembled battery 10 is started. After the discharge of the assembled battery 10 is completed (step S112), a determination is made as to whether or not the voltage deviation between the storage elements at the end of charging is greater than or equal to a predetermined threshold value (step S114). Here, if the voltage deviation is less than the threshold value, the auxiliary battery is not charged, the process moves to step 100, and charging of the assembled battery 10 is started again. On the other hand, when the voltage deviation is equal to or greater than the threshold value, the process proceeds to step S116.

  In step S116, when the charging of the assembled battery 10 is finished, the target charging end voltage that is set in advance so that the actual voltage values of all the power storage elements B1 to Bn constituting the assembled battery 10 match the target charging end voltage, and Based on the charging characteristics (approximate expression) acquired in step S106, a target charging start voltage is set for each of the power storage elements B1 to Bn. More specifically, the target charge is a value obtained by adding a deviation between the charge end voltage predicted from the charge characteristics (approximate expression) and the target charge end voltage to the voltage value before charging when charging at a predetermined time rate. Set as starting voltage. In step S116, the deviation between the charge amount obtained by integrating the approximate expression and the charge amount required for charging up to the target charge end voltage, that is, the charge amount predicted to be insufficient at the end of charge. May be set as the target supplementary charge amount.

  Next, in step S118, the photorelays R1 to Rn + 1, R21 to R24, and the DC-DC converter 20 are driven, and the storage elements until the actual voltage values of the storage elements B1 to Bn match the respective target charging start voltages. Supplementary charging is performed for each of B1 to Bn. In step S116, when the target supplementary charge amount is set instead of the target charge start voltage, in steps S118 and S120, supplementary charging is performed on power storage elements B1 to Bn according to the target supplementary charge amount.

  After the supplementary charging is completed (step S120) when the actual voltage values of the storage elements B1 to Bn match the target charging start voltage, the process moves to step S100, and charging of the assembled battery 10 is started again. And as above-mentioned, the assembled battery 10 is charged until the voltage value of electrical storage element B1-Bn corresponds with the target charge end voltage. Thereafter, the above-described steps S100 to S120 are repeatedly executed.

  Here, FIG. 5 shows an example of the charging characteristics and the target supplementary charge amount of each storage element when the assembled battery is charged without performing the auxiliary charge of the storage element. In this example, the battery pack was subjected to constant current charging at a time rate of 3 C until the voltage value of any of the power storage elements reached 4.15 (V). As shown in the upper part of FIG. 5, when the charging of the storage element is not performed, the voltage value of each storage element at the end of charging varies even though the voltage value at the start of charging is uniform. ing. Further, the target supplementary charge amount shown in the lower part of FIG. 5 is obtained by approximating the charging characteristics of each storage element linearly every 20 seconds to obtain an approximate expression, and the same voltage as the maximum voltage value of the storage element obtained from this approximate expression. This is a plot of the amount of charge required to obtain a value. The target supplementary charge amount (that is, the target supplementary charge amount with respect to the target charge end voltage) of each power storage element at the end of charge acquired in this way is 0.00 (Ah), about 0.055 (Ah), and about 0. 091 (Ah).

  Next, FIG. 6 shows a charging result when the assembled battery is charged after the auxiliary charging is performed on each power storage element by the target auxiliary charging amount shown in FIG. Here, supplementary charging was performed on each power storage element with a constant current of 200 mA. That is, the auxiliary charge was performed for 0.055 / 0.2 × 3600 = 990 seconds for the power storage element with the target auxiliary charge amount of 0.055 (Ah). Further, for the power storage element having a target supplementary charge amount of 0.091 (Ah), supplementary charge was performed for 0.091 / 0.2 × 3600 = 1638 seconds. When supplementary charging was performed before charging the assembled battery in this way, the voltage values of all the storage elements were aligned at 4.15 V (target charging end voltage) at the end of charging. From the above, the effectiveness of the present embodiment was confirmed.

  According to the present embodiment, based on the target charging end voltage and the charging characteristics of each of the storage elements B1 to Bn obtained from the change in voltage value during charging, the target charge start voltage (or target) for each of the storage elements B1 to Bn. And the battery pack 10 is charged after the voltage values (or charge amounts) of the respective storage elements B1 to Bn are adjusted based on the set target charge start voltage (or target supplement charge amount). The That is, the voltage value (or charge amount) of each power storage element B1 to Bn is adjusted before the battery pack 10 starts charging in consideration of the target charging end state and the charging characteristics of each power storage element B1 to Bn. Therefore, the voltage values of all the storage elements B1 to Bn can be made equal to the target charging end voltage at the end of charging. Further, according to the present embodiment, the voltage values (or charge amounts) of the respective storage elements B1 to Bn are independently adjusted prior to the charging of the assembled battery 10, which leads to an increase in circuit size and cost. It can also handle quick charging without any problems.

  As described above, according to the present embodiment, it is possible to reduce the voltage variation of each of the power storage elements B1 to Bn constituting the assembled battery 10 even for rapid charging without causing an increase in circuit size and cost. Therefore, the life of the assembled battery 10 can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, in the above embodiment, the polarity of the voltage output to the first bus bar 14 and the second bus bar 16 is switched using the polarity conversion matrix 22, but the insulation type DC− whose output polarity is switched by the control signal from the ECU 40. A configuration in which the polarity of the voltage output to the first bus bar 14 and the second bus bar 16 is switched by using a DC converter can also be employed.

  Moreover, in the said embodiment, although the photo relay was used as a switching element, it replaces with a photo relay and can also use semiconductor switching elements, a mechanical relay, etc., such as a transistor and FET, for example.

It is a figure which shows the whole structure of the charging device which concerns on embodiment. It is a figure which shows the structure of the voltage detection circuit which the electronic control apparatus which comprises the charging device which concerns on embodiment has. It is a figure for demonstrating the acquisition method of the charge characteristic of an electrical storage element, and an auxiliary charge method. It is a flowchart which shows the process sequence of the charging process by the charging device which concerns on embodiment. It is a graph which shows an example of the charge characteristic and target supplementary charge amount of each electrical storage element when an assembled battery is charged, without performing an auxiliary charge of an electrical storage element. It is a graph which shows an example of a charge result when charging an assembled battery after performing auxiliary charge of an electrical storage element.

Explanation of symbols

  1. Charger, 10. Battery pack, 12. Switch matrix, 20. DC-DC converter, 22. Polarity conversion matrix, 30. Charger, 40. ECU, 42. Voltage detector, 44. Charge characteristics acquisition unit, 46. Charging start state setting section, B1, B2, B3, B4, Bn-3, Bn-2, Bn-1, Bn, storage element, R1, R2, R3, R4, Rn-2, Rn-1, Rn Rn + 1, photo relay, R11, R12, R21, R22, R23, R24, photo relay.

Claims (10)

A battery pack charging device configured by connecting a plurality of power storage elements in series,
Voltage detection means for detecting the voltage value of each of the storage elements;
Based on the voltage value change during charging of each storage element detected by the voltage detection means, charging characteristic acquisition means for acquiring the charging characteristics of each storage element;
A charge start state setting means for setting a target charge state at the start of charging for each power storage element based on a preset target charge state at the end of charge and a charge characteristic acquired by the charge characteristic acquisition means; ,
Based on the target charging state at the start of charging set by the charging start state setting unit, the charging state adjusting unit that adjusts the charging state of each power storage element;
A charging device comprising: charging means for performing charging of the assembled battery after the charge state of each power storage element is adjusted by the charge state adjusting means.   The charging start state setting means sets the target charging state at the start of charging so that the charging state of all the power storage elements constituting the assembled battery coincides with the target charging state at the end of charging at the end of charging of the assembled battery. The charging device according to claim 1, wherein the charging device is set. The charging start state setting means sets a target voltage value at the start of charging for each power storage element based on the target voltage value at the end of charging and the charging characteristics,
The charge state adjusting means performs supplementary charging or discharging of each storage element so that an actual voltage value of each storage element matches a target voltage value at the start of charging. 2. The charging device according to 2. The charging start state setting means sets a target supplementary charging amount before starting charging for each power storage element based on the target voltage value at the end of charging and the charging characteristics,
3. The charging device according to claim 1, wherein the charging state adjusting unit performs auxiliary charging or discharging of each power storage element according to the target auxiliary charging amount.   The charging device according to claim 1, wherein the power storage element is a lithium ion battery. A battery pack charging method comprising a plurality of power storage elements connected in series,
A voltage detection step of detecting a voltage value of each of the storage elements;
Based on the voltage value change during charging of each storage element detected in the voltage detection step, a charging characteristic acquisition step for acquiring the charging characteristics of each storage element;
A charge start state setting step for setting a target charge state at the start of charge for each power storage element based on a preset target charge state at the end of charge and the charge characteristics acquired in the charge characteristic acquisition step; ,
A charge state adjustment step for adjusting the charge state of each of the power storage elements based on the target charge state at the start of charge set in the charge start state setting step;
And a charging step of performing charging of the assembled battery after the charging state of each power storage element is adjusted in the charging state adjusting step.   In the charging start state setting step, the target charge state at the start of charging is set so that the charge states of all the power storage elements constituting the assembled battery coincide with the target charge state at the end of charging at the end of charging of the assembled battery. The charging method according to claim 6, wherein the charging method is set. The charging start state setting step sets a target voltage value at the start of charging for each power storage element based on the target voltage value at the end of charging and the charging characteristics,
The charge state adjusting step performs supplementary charging or discharging of each of the storage elements so that an actual voltage value of each of the storage elements matches a target voltage value at the start of charging. 8. The charging method according to 7. In the charging start state setting step, based on the target voltage value at the end of charging and the charging characteristics, a target supplementary charging amount before starting charging is set for each power storage element,
8. The charging method according to claim 6, wherein in the charging state adjustment step, each of the power storage elements is subjected to auxiliary charging or discharging according to the target auxiliary charging amount.   The charging method according to claim 6, wherein the power storage element is a lithium ion battery.

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